While the field of MIMO transmission has been explored over the past decade mainly theoretically, relatively few results exist on how these transmissions perform over realistic, imperfect channels. The reason for this is that measurement equipment is expensive, difficult to obtain, and often inflexible when a multitude of transmission parameters are of interest. This paper presents a flexible testbed developed to examine MIMO algorithms and channel models described in literature by transmitting data at 2.45 GHz through real, physical channels, supporting simultaneously four transmit and four receive antennas. Operation is performed directly from Matlab allowing for a cornucopia of real-world experiments with minimum effort. Examples measuring bit error rates on space-time block codes are provided in the paper.